The present invention relates to a semi-annular-shaped half thrust bearing having a sliding surface for receiving an axial force of a crankshaft of an internal combustion engine.
A crankshaft of an internal combustion engine is rotatably supported in its journal part by a lower portion of a cylinder block of the engine via a main bearing constituted by a pair of half bearings combined into a cylindrical shape. One or both of the pair of half bearings are combined with a half thrust bearing for receiving an axial force of the crankshaft. A half thrust bearing/thrust bearings is/are placed on one or both of end faces in an axial direction of the half bearing.
The half thrust bearing receives an axial force generated in an axial direction of the crankshaft. That is, the half thrust bearing is provided for the purpose of bearing an axial force on the crankshaft, for example, when the crankshaft is connected to a transmission by a clutch.
The crankshaft of the internal combustion engine is supported in its journal part by the lower portion of the cylinder block of the engine via the main bearing constituted by the pair of half bearings. Lubrication oil is fed from an oil gallery in a cylinder block wall via a through hole in a wall of the main bearing into a lubrication oil groove formed along an inner surface of the main bearing. Thus, the lubrication oil is supplied into the lubrication oil groove of the main bearing and is then supplied to the half thrust bearing,
In recent years, an oil pump for supplying lubrication oil has been downsized in order to improve fuel economy of the internal combustion engine, and this causes a reduction in an amount of lubrication oil supplied to the bearings. Accordingly, the amount of lubrication oil leaked from end faces of the main bearing decreases, and thus the amount of lubrication oil supplied to the half thrust bearing also tends to decrease. In order to address this problem, for example, a technique has been proposed in which retainability of lubrication oil is improved by forming thin grooves in parallel to each other on a sliding surface of the half thrust bearing (see JP 2001-323928A, for example) or by forming a plurality of minute recesses on a sliding surface of the half thrust bearing (see JP 2000-504089A, for example).